1. Field of the Invention
The present invention generally relates to an air conditioner system and, more particularly, to an air conditioner which can also be used for heating by employing a refrigerant heater as a heat source.
2. Description of the Related Art
A heat pump refrigeration cycle system air conditioner, for performing a heating operation by employing a refrigerant heater as a heat source, has been conventionally known.
In such an air conditioner, a heating operation is normally preced by a refrigerant mass recovery operation, performed during a predetermined time period before the start of the heating operation.
This is because, during a refrigeration cycle of an air conditioner of this type, a finite quantity of refrigerant remains stored in an outdoor heat exchanger having a lowest ambient temperature. This refrigerant must be withdrawn from the outdoor heat exchanger and added to the remainder of the system prior to a heating operation.
If a heating operation is started without first performing a refrigerant mass recovery operation, the mass flow of refrigerant which circulates in the refrigeration cycle may be insufficient. If the flow through the refrigerant heater is too low, the refrigerant may become overheated, and a stable heating operation cannot be achieved.
When the refrigerant mass recovery operation is performed, a smooth shift to a stable heating operation can be achieved. However, the start of the heating operation will be delayed by the time period required to preform the refrigerant mass recovery operation. This delay is inconvenient for a user.
Moreover because the refrigerant mass recovery operation in the conventional air conditioner is performed at the start of the heating operation regardless of the refrigerant's pressure or temperature, the user may incur further undue delay.
In other words, when the outside ambient temperature is low, or when a heating operation is started after the air conditioner has not been used for a long period of time, the refrigerant mass recovery operation must be executed. However, these two conditions necessitating the need for performing the refrigerant mass recovery operation are not always present.